[gta02-core] PMU cleanup

Werner Almesberger werner at openmoko.org
Wed Aug 19 20:24:53 CEST 2009

?lvaro Lopes wrote:
> * GSM_ON is a global label, but only used inside PMU. We should switch
> to a local label, and maybe move R1729 near U1703.

Sounds good.

> * nGSM_OC is not used any more ? It was connected to EINT19, but due to
> ECN0001, we are using this GPIO for board revision check. What was the
> purpose of this signal ?

Hmm, that change doesn't look so good. Spending EINTs on the board
revision sounds like a horrible waste to me. (Ah, another task for
the MPU: record the board revision :)

nGSM_OC basically tells us that the power switch has current-limited
the modem. This is an abnormal condition, that should never occur. If
it does, there's either a hardware defect or a design flaw.

So it's not a signal we strictly need. However, since we have it, we
may as well connect it. If there's modem trouble, it may help to
rule out some failure scenarios.

Now, with the GE865, the whole arrangement may have to change, but we
have to find out about the current requirements on each rail. The
GE865 has separate power inputs for the baseband processor and the RF
amplifier, just like our Calypso circuit does, so it may be possible
to use the same concept.

- Werner

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